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Even though Randy seems to think this is adequate, digital scales with 0.01g sensitivity can be purchased for under $20. Also, while I don't know what Randy has in mind for accurate volume measurement, I would consider something like a 1000 mL Class A volumetric flask to be a requirement for a project like this. If you're going to go to all the trouble to do this, you might as well spend just a little more money to get decent tools that will greatly improve the accuracy of the resulting standards (especially if serial dilutions are involved). Just my $0.02.I do have a standard kitchen scale which measures in grams.
The short answer is... this will work as long as the instrument is precise and accurate enough...The BRS video demonstrated this.
Actually I have been working on this problem for several months doing almost the exact procedure you outlined. I chose to use the HANNA Checkers and a HANNA Hand Held Spectrophotometer....They are much lower cost,although they are not programmable.
Here is my post that I made in October https://www.reef2reef.com/threads/diy-nitrate-test-meter.330892/#post-4114495
I have continued to work on this and have gotten some encouraging results. I have been focusing on the Nitrate and Iodine tests. I am satisfied with the HANNA Phosphorous Checker result I and getting so I did not include this test. I will be posting shortly my updated results on the Nitrate test. I have been focusing on the low range values for nitrate... 0-2 ppm because my initial work indicated that it was not reliable at these low levels (see October post) . My procedure is a bit different in that I run my calibration standards in saltwater then measure them and record the values on the different Checkers and Hand Held Spectrophotometers (HI-96702 Copper High Range). I then create a regression equation using Excel or a program called MyCurveFit and analize the equation for fit and estimate error. I pick the best one and used it as a predictor.
Because these are not programmable instruments I put the equation into Excel and enter the results of the meter reading and it gives me a projected value based on the regression equation...So I guess you could say Excel is the programmable feature of the instrument I have been using this on my nitrate test for several weeks and comparing it to other tests as a reference (NYOS, Red Sea Pro and some outside testing services) I have not explored all of the Hanna Checkers but have found the HI-736 Low Range Phosphorous Checker in conjunction with the Red Sea reagents and procedure works well for low range nitrate. The Iodine test is a bit more difficult because it is time temperature dependent. That being said, I think it is doable. My initial results indicate it can be repeatable and reproducible...The question remains how accurate is it, which I am still working on.
I will be posting the latest updates in the next few days...
Rick,
You are obviously way ahead. I am going to read your post over again later to make sure I get it all. And of course I will come back to it later when I start getting some results.
Randy,
I picked up:
Loudwolf, TriSodium Phosphate (TSP) Na3PO4 99.9+% Ultra-Pure food grade
Shor, Sodium Nitrate, Reagent Grade (chemically pure) – 1 lb. bag
I actually have access to a photospectrometer at work which I can borrow so I can test this out with a pretty low overhead.
Anyway, I guess this is really good practice for "testing" my test kits and methods.
And now that I am thinking along these lines..
I am not sure if it's even possible for all of the parameters, but it seems like it would be a great reef chemistry project to put together a spreadsheet with recipes for preparing reference solutions for all of the basic parameters.
Ca
Alk
Mg
Ph
Nitrate
Salinity (OK, I'll work on this one.)
It seems like these would be useful to a lot of reefers.
Rick,
Did you find inexpensive tips that fit the Four E micro-pipettes?
Calling all you chemists,
Am I on the right track for making 1 liter of a 0.1% reference solution for NaNO3 and Na3PO4
Yes, I will have to either start with a tenth or hundredth of a gram and then then dilute. I've ordered a more precise scale and will be getting the micro-pipettes. It's been a very long time since I've done anything like this and I just wanted to check that I'm headed in the right direction.
Jim and Rick thanks for the feedback.
Rick and Jim thanks for the feedback.
Yes, I am definitely aware that I will need to dilute the solution down to ppm or ppb.
I have ordered a new scale and plan on getting those micro-pipettes.
I just wanted to weigh in and see if my general approach was correct before I start worrying about the details.
Yes, I will have to either start with a tenth or hundredth of a gram and then then dilute. I've ordered a more precise scale and will be getting the micro-pipettes. It's been a very long time since I've done anything like this and I just wanted to check that I'm headed in the right direction.
Jim and Rick thanks for the feedback.
Yes, I will have to either start with a tenth or hundredth of a gram and then then dilute. I've ordered a more precise scale and will be getting the micro-pipettes. It's been a very long time since I've done anything like this and I just wanted to check that I'm headed in the right direction.
Jim and Rick thanks for the feedback.